JP3625388B2 - Thermal transfer recording medium - Google Patents

Description

【００２２】
実施例２
実施例１において、インク層の成分として下記のものを使用した以外は、実施例１と同様にして熱転写記録媒体を作成した。

【００２５】
比較例１
実施例１において、インク層の成分として下記のものを使用した以外は、実施例１と同様にして熱転写記録媒体を作成した。

【００２６】
比較例２
実施例１において、インク層の成分として下記のものを使用した以外は、実施例１と同様にして熱転写記録媒体を作成した。

【００２７】
これら実施例及び比較例の６種の熱転写記録媒体において、以下の条件で印字を行なった。
（サーマルヘッド） 端面ラインサーマルヘッド（剥離距離２１０μｍ）
（印字速度） １２５ｍｍ／ｓｅｃ
（受容体） 白色ＰＥＴ
以上の条件で印字した画像の耐エタノール性の片字画像において、図１に示すＪＩＳ Ｌ ８０３の方法により以下の条件で耐エタノール性試験を行なった。
（試験片面積） ２ｃｍ×５ｃｍ
（試験片面積） １ｋｇ
（綿布） かなきん３号にエタノールを浸み込ませたもの
評価は、上記条件でこすり、画像がかすれる迄のこすり回数（往復回数ではない）を測定した。
【００２８】
【表１】

【００２９】
【発明の効果】
本発明の熱転写記録媒体は、インク層中に熱溶融性樹脂としてポリエステル樹脂を、また着色剤の分散剤として反応性官能基を幹部分に有するグラフトポリマーを含有させたことにより、それを用いた転写画像の耐薬品性、特に耐エタノール性に極めて優れたものである。
【図面の簡単な説明】
【図１】熱転写記録媒体を用いて形成した転写画像の耐エタノール性を評価するための評価方法の概略図。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermal transfer recording medium, and more particularly to a thermal transfer recording medium that provides a highly reliable transfer image having excellent chemical resistance.
[0002]
[Prior art]
In recent years, a thermal transfer recording method using a thermal head is often used due to advantages such as noiselessness, relatively inexpensive and small-sized apparatus, easy maintenance, and stable transfer image. Has come to be. Examples of the thermal transfer recording medium used in such a thermal transfer recording method include waxes such as natural wax and synthetic wax on one side of a substrate having excellent thermal conductivity and heat resistance, such as condenser paper and polyester film, and coloring. Agents, thermoplastic resins, etc. are mixed or laminated to provide a heat-meltable color material layer.
However, a transfer image by a thermal transfer recording medium provided with a heat-meltable color material layer using the above-mentioned conventional material is eluted with a solvent such as alcohol, kerosene, machine oil, oil, or a cloth containing these solvents. There was a drawback that it disappeared when rubbed.
[0003]
As an improvement in these chemical resistances,
{Circle around (1)} Acrylic, phenolic, xylene and cellulose resins are used as the surface layer.
(2) JP-A-63-296984 Styrene having a number average molecular weight of 1000 to 5000 is used as the surface adhesive layer.
{Circle around (3)} JP-A-2-192993 A polyester resin (mp or softening point of 55 to 120 ° C.) and chlorinated paraffin (mp or softening point of less than 55 ° C.) are contained in the ink layer.
However, in any case, sufficient chemical resistance cannot be obtained.
[0004]
As described above, a number of thermal transfer recording media aimed at improving chemical resistance have been proposed in addition to those described above, but none of them has sufficient quality.
[0005]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION An object of the present invention is to provide a thermal transfer recording medium having a colorant dispersion ability and excellent in chemical resistance (particularly ethanol resistance) of a printed image by various thermal transfer systems.
[0006]
[Means for solving problems]
According to the present invention, in a thermal transfer recording medium in which a release layer mainly composed of wax and an ink layer containing a colorant and a heat-meltable resin are provided on one surface of a support in this order, A graft polymer having a polyester resin as a meltable resin and a reactive functional group in the trunk as a dispersant for a colorant (a graft polymer having an ethylene-glycidyl methacrylate copolymer as a trunk and polystyrene as a branch and / or epoxy-modified) There is provided a thermal transfer recording medium comprising a graft polymer having polystyrene as a trunk portion and polystyrene as a branch portion . In addition, according to the present invention, there is provided the thermal transfer recording medium, wherein the polyester resin has a weight average molecular weight of 16000 or less.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail.
A feature of the present invention is that in a thermal transfer recording medium in which a release layer mainly composed of wax on a support, an ink layer containing a colorant and a heat-meltable resin are sequentially laminated, a polyester resin is used as the heat-meltable resin, In addition, a graft polymer having a reactive functional group in the trunk portion is used as a dispersant for the colorant.
[0008]
In the present invention, the polyester resin as the heat-meltable resin used in the ink layer is a polycondensation of a polybasic acid or a derivative thereof such as a lower alcohol ester or an acid halide with a polyhydric alcohol, or a cyclic such as a lactone. It is a polyester resin produced by a generally known synthesis method such as ring-opening polymerization of an ester.
Among such polyester resins, the weight average molecular weight (Mw) is preferably 5000 to 3000, and more preferably 16000 or less.
By keeping the weight average molecular weight (Mw) of the polyester resin as low as 16000 or less, the transfer property to the receiving paper is improved and the adhesive strength to the receptor is also improved, so that the chemical resistance is improved.
The Tg of the polyester resin is preferably 20 to 60 ° C.
[0009]
In the present invention, the dispersant for the colorant used in the ink layer includes a graft polymer having an ethylene-glycidyl methacrylate copolymer as a trunk and polystyrene as a branch, and a graft polymer having an epoxy-modified polystyrene as a trunk and polystyrene as a branch. Etc.
[0010]
Thus, in the present invention, as a dispersant for the colorant , a graft polymer having an ethylene-glycidyl methacrylate copolymer as a trunk and polystyrene as a branch and / or an epoxy-modified polystyrene as a trunk and polystyrene as a branch. By using a polymer , both the dispersibility of carbon and the compatibility of the polyester resin can be improved. For example, by using a graft polymer using epoxy-modified polystyrene for the trunk portion of the graft polymer, the carbon dispersibility due to the ring opening of the epoxy group is maximized, the compatibility with the polyester resin is maximized, and the polystyrene resistance Since the ethanol property is good, scratch resistance such as scratches at the pen tip is also good.
[0011]
As the colorant used in the present invention, an appropriate one can be selected from carbon black, organic pigments, inorganic pigments or various dyes according to the required color tone.
[0012]
Various additives such as wax, plasticizer, and solvent may be further added to the ink layer of the present invention for the purpose of improving thermal transferability and resolution.
For example, the addition of wax-like fatty acid amides, synthetic waxes such as paraffin wax, natural waxes such as candelilla wax and carnauba wax, and oils such as silicone oil and perfluoroalkyl ether can improve thermal transferability and resolution. Can be improved. Diesters and the like as plasticizers, phosphate esters and the like as lubricants, resins such as silicone resins, tetrafluoroethylene resins and fluoroalkyl ether resins, and inorganic lubricants such as silicon carbide and silica may be used. it can.
[0013]
Next, the release layer is a layer provided adjacent to the support, and is mainly composed of a wax having a melting point or softening point of 70 to 120 ° C. This layer is provided in order to improve the peelability between the support and the thermal transfer layer when heat is applied. Therefore, it is desirable that the layer is composed of a component that melts into a low-viscosity liquid when heat is applied by a thermal head. The layer components may be adjusted so that the layer is easily cut near the interface between the heated part and the non-heated part.
[0014]
Specific examples of the wax used in the release layer include natural waxes such as beeswax, whale wax, wood wax, rice bran wax, carnauba wax, candelilla wax, and montan wax; paraffin wax, microcrystalline wax, oxidation Synthetic waxes such as wax, ozokerite, ceresin, ester wax, polyethylene wax: higher saturated fatty acids such as margaric acid, lauric acid, myristic acid, palmitic acid, stearic acid, furoic acid, behenic acid; higher saturated fatty acids such as stearyl alcohol and behenyl alcohol Monohydric alcohols; higher esters such as sorbitan fatty acid esters; higher fatty acid amides such as stearic acid amide and oleic acid amide.
[0015]
It is also possible to give the release layer elasticity to improve the adhesion between the thermal transfer recording medium and the receptor. To achieve this object, the release layer is made of isoprene rubber, butadiene rubber, ethylene propylene rubber, Rubbers such as butyl rubber and nitrile rubber can be added.
In addition, resins having strong adhesiveness can be added to the layer to prevent the release layer from falling off. For this purpose, an ethylene-vinyl acetate copolymer, an ethylene-ethyl acrylate copolymer, or the like is suitable as the resin to be added.
[0016]
The support may be a known film or paper as it is, for example, a polyester film such as polyethylene terephthalate (PET), polycarbonate, triacetyl cellulose, nylon, polyimide, etc., a relatively good heat-resistant plastic film; cellophane; sulfuric acid Paper or the like is preferably used.
[0017]
Further, the thermal transfer recording medium of the present invention may be provided with a protective layer (back layer) on the back surface of the support, if necessary. The protective layer is a layer to protect the support from high temperature when heat is applied by the thermal head. In addition to highly heat-resistant thermoplastic resins and thermosetting resins, UV curable resins and electron beam curable resins can also be used. It is.
Resins suitable for forming the protective layer are fluorine resin, silicone resin, polyimide resin, epoxy resin, phenol resin, melamine resin, and the like, and these resins may be used in a thin film form.
In addition, since the heat resistance of the support can be remarkably improved by installing the protective layer, it becomes possible to use a material that has been conventionally unsuitable by installing the layer as the support.
[0018]
Furthermore, in the thermal transfer recording medium of the present invention, an under layer can be provided between the support and the release layer.
[0019]
Installation of a release layer, an ink layer, a protective layer, a back layer, an under layer, and the like on a support can be performed by a known method such as a hot melt coating method, an aqueous coating method, or a coating method using an organic solvent. it can. The total thickness of the thermal transfer layer provided by such a coating method is 0.5 to 10 μm, preferably 0.5 to 6.0 μm, and the ink layer thickness in the thermal transfer layer is preferably 0.5 to 6.0 μm, preferably 1.0 to 40 μm, the release layer thickness is 0.3 to 2.0 μm, preferably 0.5 to 1.5 μm, and the under layer may be 0.05 to 0.40 μm.
[0020]
【Example】
Hereinafter, based on an Example and a comparative example, this invention is demonstrated concretely.
Parts are based on weight.
[0021]
Example 1
Using 4.5 μm polyethylene terephthalate as a support,
The components of the following undercoat layer (0.2 μm thick), release layer (1.0 μm thick), and ink layer (1.0 μm) are coated on this support in order from the support side, dried using methyl ethyl ketone as a solvent, and subjected to thermal transfer. A recording medium was created.
The ink layer component was applied at a solid content of 15%.

[0022]
Example 2
A thermal transfer recording medium was prepared in the same manner as in Example 1 except that the following ink layer components were used in Example 1.

[0025]
Comparative Example 1
A thermal transfer recording medium was prepared in the same manner as in Example 1 except that the following ink layer components were used in Example 1.

[0026]
Comparative Example 2
A thermal transfer recording medium was prepared in the same manner as in Example 1 except that the following ink layer components were used in Example 1.

[0027]
Printing was performed under the following conditions on the six types of thermal transfer recording media of these examples and comparative examples.
(Thermal head) End line thermal head (peeling distance 210 μm)
(Printing speed) 125mm / sec
(Receptor) White PET
The ethanol resistance test was performed on the following conditions under the method of JIS L803 shown in FIG.
(Specimen area) 2cm x 5cm
(Specimen area) 1kg
(Cotton cloth) Kanakin No. 3 was soaked in ethanol by rubbing under the above conditions, and measuring the number of rubbing (not the number of reciprocations) until the image was smeared.
[0028]
[Table 1]

[0029]
【The invention's effect】
The thermal transfer recording medium of the present invention uses a polyester resin as a heat-meltable resin in the ink layer and a graft polymer having a reactive functional group in the trunk as a dispersant for the colorant. The transfer image has excellent chemical resistance, particularly ethanol resistance.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of an evaluation method for evaluating ethanol resistance of a transfer image formed using a thermal transfer recording medium.

Claims (2)

In a thermal transfer recording medium in which a release layer mainly composed of wax and an ink layer containing a colorant and a heat-meltable resin are provided on one surface of a support in this order, a polyester resin as the meltable resin in the ink layer In addition, as a colorant dispersant , a graft polymer having an ethylene-glycidyl methacrylate copolymer as a trunk and polystyrene as a branch part and / or a graft polymer having an epoxy-modified polystyrene as a trunk part and a polystyrene as a branch part are contained. A thermal transfer recording medium characterized by the above. The thermal transfer recording medium according to claim 1, wherein the polyester resin has a weight average molecular weight of 16000 or less.

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